Considerable success has been achieved in recent years in the repair of injured nerves, including those wherein complete severance of a nerve trunk has occurred. Microsurgery has enhanced the ability to match nerve ends precisely, but itself introduces additional trauma. Success of nerve repair is uncertain at best, not only because of surgical difficulties but also because of the many interrelated biological events occurring at the site of injury and beyond the site of injury.
Functional recovery after nerve repair is dependent on structural and functional events in the peripheral as well as the central nervous system. The pattern of cellular and biochemical events required to achieve useful sensory and motor regeneration after a nerve injury is complex. Among necessary factors are survival of the nerve cell body, initiation of the sprouting process, growth of sprouts over the zone of injury, reinnervation of endoneurial tubes in the distal segment, reinnervation of peripheral targets and maturation of nerve fibers/target structures.
Some of these problems can be approached surgically. The surgeon can influence the result by the way he or she handles the damaged nerve and by the method chosen for reconstruction. Other factors susceptible to influence are the timing of surgery and postoperative reeducation and rehabilitation. At present the remaining components of the regeneration process are more or less out of reach, but some may prove to be critical factors to address in the future.